DESCRIPTION: As bone marrow transplantation becomes one of the preferred treatments for life-threatening diseases of the blood, increasing numbers of patients must seek compatible marrow from unrelated donors. The low probability of finding a good patient-donor marrow match means that between one- to two-thirds of ill patients never locate a donor with perfectly compatible marrow. Furthermore, once volunteers are identified as a preliminary match for a patient, 30 to 40 percent are either unwilling or medically unable to actually donate marrow. Thus, volunteer attrition contributes significantly to the problems already inherent in finding a suitable donor candidate. Despite the critical importance of maintaining a large registry of unrelated volunteer donor candidates, no systematic studies of factors affecting the successful retention of such volunteers exists. The study proposed is designed to identify factors that affect the National Marrow Donor Program's (NMDP) success in retention of bone marrow volunteers. In particular, this study will examine the relationship of volunteer characteristics and donor center factors to volunteer psychological outcomes during two critical stages in the blood testing process and to donor center rates of volunteer cooperation at these stages. Longitudinal and cross-sectional survey data will be gathered from a total of 2,600 potential marrow donors who are at one of two critical decision points in the process leading to donation (DR-blood-typing, CT-blood-typing), and from personnel at the 100 NMDP donor centers. These data will allow the investigators to (a) describe the distribution and interrelationships between donor center structural characteristics and the strategies centers utilize for volunteer recruitment and retention, (b) determine which donor center factors (both structural and tactical) and volunteer background characteristics best predict positive volunteer-specific psychological outcomes at later typing stages, and examine and revise models of individual volunteer-specific outcomes and aggregate across-center retention rates. Study findings will promote better understanding of the donor management organizational characteristics that are central to successful retention of marrow volunteers, inform the revision of conceptual models of medical volunteerism, and guide future efforts to secure donors across the full range of living-organ donation.